A Phase II randomized controlled trial for lung and diaphragm protective ventilation (Real-time Effort Driven VENTilator management)

Phenotypes based on respiratory drive and effort to identify the risk factors when P0.1 fails to estimate ∆PES in ventilated children

BACKGROUND

Monitoring respiratory effort and drive during mechanical ventilation is needed to deliver lung and diaphragm protection. Esophageal pressure (∆PES) is the gold standard measure of respiratory effort but is not routinely available. Airway occlusion pressure in the first 100 ms of the breath (P0.1) is a readily available surrogate for both respiratory effort and drive but is only modestly correlated with ∆PES in children. We sought to identify risk factors for P0.1 over or underestimating ∆PES in ventilated children.

METHODS

Secondary analysis of physiological data from children and young adults enrolled in a randomized controlled trial testing lung and diaphragm protective ventilation in pediatric acute respiratory distress syndrome (PARDS) (NCT03266016). ∆PES (∆PES-REAL), P0.1 and predicted ∆PES (∆PES-PRED = 5.91*P0.1) were measured daily to identify phenotypes based upon the level of respiratory effort and drive: one passive (no spontaneous breathing), three where ∆PES-REAL and ∆PES-PRED were aligned (low, normal, and high effort and drive), two where ∆PES-REAL and ∆PES-PRED were mismatched (high underestimated effort, and overestimated effort). Logistic regression models were used to identify factors associated with each mismatch phenotype (High underestimated effort, or overestimated effort) as compared to all other spontaneous breathing phenotypes.

RESULTS

We analyzed 953 patient days (222 patients). ∆PES-REAL and ∆PES-PRED were aligned in 536 (77%) of the active patient days. High underestimated effort (n = 119 (12%)) was associated with higher airway resistance (adjusted OR 5.62 (95%CI 2.58, 12.26) per log unit increase, p < 0.001), higher tidal volume (adjusted OR 1.53 (95%CI 1.04, 2.24) per cubic unit increase, p = 0.03), higher opioid use (adjusted OR 2.4 (95%CI 1.12, 5.13, p = 0.024), and lower set ventilator rate (adjusted OR 0.96 (95%CI 0.93, 0.99), p = 0.005). Overestimated effort was rare (n = 37 (4%)) and associated with higher alveolar dead space (adjusted OR 1.05 (95%CI 1.01, 1.09), p = 0.007) and lower respiratory resistance (adjusted OR 0.32 (95%CI 0.13, 0.81), p = 0.017).

CONCLUSIONS

In patients with PARDS, P0.1 commonly underestimated high respiratory effort particularly with high airway resistance, high tidal volume, and high doses of opioids. Future studies are needed to investigate the impact of measures of respiratory effort, drive, and the presence of a mismatch phenotype on clinical outcome.

TRIAL REGISTRATION

NCT03266016; August 23, 2017.

Noninvasive Surrogate for Physiologic Dead Space Using the Carbon Dioxide Ventilatory Equivalent: Testing in a Single-Center Cohort, 2017-2023

OBJECTIVES

We sought to evaluate the association between the carbon dioxide ( co2 ) ventilatory equivalent (VEq co2 = minute ventilation/volume of co2 produced per min), a marker of dead space that does not require a blood gas measurement, and mortality risk. We compared the strength of this association to that of physiologic dead space fraction (V D /V t = [Pa co2 -mixed-expired P co2 ]/Pa co2 ) as well as to other commonly used markers of dead space (i.e., the end-tidal alveolar dead space fraction [AVDSf = (Pa co2 -end-tidal P co2 )/Pa co2 ], and ventilatory ratio [VR = (minute ventilation × Pa co2 )/(age-adjusted predicted minute ventilation × 37.5)]).

DESIGN

Retrospective cohort data, 2017-2023.

SETTING

Quaternary PICU.

PATIENTS

One hundred thirty-one children with acute respiratory distress syndrome.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

All dead space markers were calculated at the same 1-minute timepoint for each patient within the first 72 hours of using invasive mechanical ventilation. The 131 children had a median (interquartile range, IQR) age of 5.8 (IQR 1.4, 12.6) years, oxygenation index (OI) of 7.5 (IQR 4.6, 14.3), V D /V t of 0.47 (IQR 0.38, 0.61), and mortality was 17.6% (23/131). Higher VEq co2 ( p = 0.003), V D /V t ( p = 0.002), and VR ( p = 0.013) were all associated with greater odds of mortality in multivariable models adjusting for OI, immunosuppressive comorbidity, and overall severity of illness. We failed to identify an association between AVDSf and mortality in the multivariable modeling. Similarly, we also failed to identify an association between OI and mortality after controlling for any dead space marker in the modeling. For the 28-day ventilator-free days outcome, we failed to identify an association between V D /V t and the dead space markers in multivariable modeling, although OI was significant.

CONCLUSIONS

VEq co2 performs similarly to V D /V t and other surrogate dead space markers, is independently associated with mortality risk, and may be a reasonable noninvasive surrogate for V D /V t .

Estimation of inspiratory effort using airway occlusion maneuvers in ventilated children: a secondary analysis of an ongoing randomized trial testing a lung and diaphragm protective ventilation strategy

BACKGROUND

Monitoring respiratory effort in ventilated patients is important to balance lung and diaphragm protection. Esophageal manometry remains the gold standard for monitoring respiratory effort but is invasive and requires expertise for its measurement and interpretation. Airway pressures during occlusion maneuvers may provide an alternative, although pediatric data are limited. We sought to determine the correlation between change in esophageal pressure during tidal breathing (∆Pes) and airway pressure measured during three airway occlusion maneuvers: (1) expiratory occlusion pressure (Pocc), (2) airway occlusion pressure (P0.1), and (3) respiratory muscle pressure index (PMI) in children. We also sought to explore pediatric threshold values for these pressures to detect excessive or insufficient respiratory effort.

METHODS

Secondary analysis of physiologic data from children between 1 month and 18 years of age with acute respiratory distress syndrome enrolled in an ongoing randomized clinical trial testing a lung and diaphragm protective ventilation strategy (REDvent, R01HL124666). ∆Pes, Pocc, P0.1, and PMI were measured. Repeated measure correlations were used to investigate correlation coefficients between ∆Pes and the three measures, and linear regression equations were generated to identify potential therapeutic thresholds.

RESULTS

There were 653 inspiratory and 713 expiratory holds from 97 patients. Pocc had the strongest correlation with ∆Pes (r = 0.68), followed by PMI (r = 0.60) and P0.1 (r = 0.42). ∆Pes could be reliably estimated using the regression equation ∆Pes = 0.66 [Formula: see text] Pocc (R2 = 0.82), with Pocc cut-points having high specificity and moderate sensitivity to detect respective ∆Pes thresholds for high and low respiratory effort. There were minimal differences in the relationship between Pocc and ∆Pes based on age (infant, child, adolescent) or mode of ventilation (SIMV versus Pressure Support), although these differences were more apparent with P0.1 and PMI.

CONCLUSIONS

Airway occlusion maneuvers may be appropriate alternatives to esophageal pressure measurement to estimate the inspiratory effort in children, and Pocc represents the most promising target.

TRIAL REGISTRATION

NCT03266016; August 23, 2017.

Fundamental concepts and the latest evidence for esophageal pressure monitoring

Transpulmonary pressure is an essential physiologic concept as it reflects the true pressure across the alveoli, and is a more precise marker for lung stress. To calculate transpulmonary pressure, one needs an estimate of both alveolar pressure and pleural pressure. Airway pressure during conditions of no flow is the most widely accepted surrogate for alveolar pressure, while esophageal pressure remains the most widely measured surrogate marker for pleural pressure. This review will cover important concepts and clinical applications for esophageal manometry, with a particular focus on how to use the information from esophageal manometry to adjust or titrate ventilator support. The most widely used method for measuring esophageal pressure uses an esophageal balloon catheter, although these measurements can be affected by the volume of air in the balloon. Therefore, when using balloon catheters, it is important to calibrate the balloon to ensure the most appropriate volume of air, and we discuss several methods which have been proposed for balloon calibration. In addition, esophageal balloon catheters only estimate the pleural pressure over a certain area within the thoracic cavity, which has resulted in a debate regarding how to interpret these measurements. We discuss both direct and elastance-based methods to estimate transpulmonary pressure, and how they may be applied for clinical practice. Finally, we discuss a number of applications for esophageal manometry and review many of the clinical studies published to date which have used esophageal pressure. These include the use of esophageal pressure to assess lung and chest wall compliance individually which can provide individualized information for patients with acute respiratory failure in terms of setting PEEP, or limiting inspiratory pressure. In addition, esophageal pressure has been used to estimate effort of breathing which has application for ventilator weaning, detection of upper airway obstruction after extubation, and detection of patient and mechanical ventilator asynchrony.

A 30-Minute Spontaneous Breathing Trial Misses Many Children Who Go On to Fail a 120-Minute Spontaneous Breathing Trial

BACKGROUND

The optimal length of spontaneous breathing trials (SBTs) in children is unknown.

RESEARCH QUESTIONS

What are the most common reasons for SBT failure in children, and when do they occur? Can clinical parameters at the 30-min mark of a 120-min SBT predict outcome?

STUDY DESIGN AND METHODS

We performed a secondary analysis of a clinical trial in pediatric ARDS, in which 2-h SBTs are conducted daily. SBT failure is based on objective criteria, including esophageal manometry for effort of breathing, categorized as passage, early failure (≤ 30 min), or late failure (30-120 min). Spirometry was used to calculate respiratory rate (RR), tidal volume (Vt), and rapid shallow breathing index (RSBI), in addition to pulse oximetry and capnography. Predictive models evaluated parameters at 30 min against SBT outcome, using receiver operating characteristic plots and area under the curve.

RESULTS

We included 100 children and 305 SBTs, with 42% of SBTs being successful, 32% failing within 30 min, and 25% failing between 30 and 120 min. Of the patients passing SBTs at 30 min, 40% went on to fail by 120 min. High respiratory effort (esophageal manometry) was present in > 80% of failed SBTs. At the 30-min mark, there were no clear thresholds for RR, Vt, RSBI, Fio2, oxygen saturation, or capnography that could reliably predict SBT outcome. Multivariable modeling identified RR (P < .001) and RSBI > 7 (P = .034) at 30 min, pre-SBT inspiratory pressure level (P = .009), and pre-SBT retractions (P = .042) as predictors for SBT failure, but this model performed poorly in an independent validation set with the receiver operating characteristic plot crossing the reference line (area under the curve, 0.67).

INTERPRETATION

A 30-min SBT may be too short in children recovering from pediatric ARDS because many go on to fail between 30 and 120 min. Reassuring values of Vt, RR, and gas exchange at 30 min do not reliably predict SBT passage at 2 h, likely because they do not capture the effort of breathing.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov; No.: NCT03266016; URL: www.

CLINICALTRIALS

gov.

Pleural and transpulmonary pressures to tailor protective ventilation in children

This review aims to: (1) describe the rationale of pleural (P_PL) and transpulmonary (P_L) pressure measurements in children during mechanical ventilation (MV); (2) discuss its usefulness and limitations as a guide for protective MV; (3) propose future directions for paediatric research. We conducted a scoping review on P_L in critically ill children using PubMed and Embase search engines. We included peer-reviewed studies using oesophageal (P_ES) and P_L measurements in the paediatric intensive care unit (PICU) published until September 2021, and excluded studies in neonates and patients treated with non-invasive ventilation. P_L corresponds to the difference between airway pressure and P_PL Oesophageal manometry allows measurement of P_ES, a good surrogate of P_PL, to estimate P_L directly at the bedside. Lung stress is the P_L, while strain corresponds to the lung deformation induced by the changing volume during insufflation. Lung stress and strain are the main determinants of MV-related injuries with P_L and P_PL being key components. P_L-targeted therapies allow tailoring of MV: (1) Positive end-expiratory pressure (PEEP) titration based on end-expiratory P_L (direct measurement) may be used to avoid lung collapse in the lung surrounding the oesophagus. The clinical benefit of such strategy has not been demonstrated yet. This approach should consider the degree of recruitable lung, and may be limited to patients in which PEEP is set to achieve an end-expiratory P_L value close to zero; (2) Protective ventilation based on end-inspiratory P_L (derived from the ratio of lung and respiratory system elastances), might be used to limit overdistention and volutrauma by targeting lung stress values < 20-25 cmH₂O; (3) P_PL may be set to target a physiological respiratory effort in order to avoid both self-induced lung injury and ventilator-induced diaphragm dysfunction; (4) P_PL or P_L measurements may contribute to a better understanding of cardiopulmonary interactions. The growing cardiorespiratory system makes children theoretically more susceptible to atelectrauma, myotrauma and right ventricle failure. In children with acute respiratory distress, P_PL and P_L measurements may help to characterise how changes in PEEP affect P_PL and potentially haemodynamics. In the PICU, P_PL measurement to estimate respiratory effort is useful during weaning and ventilator liberation. Finally, the use of P_PL tracings may improve the detection of patient ventilator asynchronies, which are frequent in children. Despite these numerous theoritcal benefits in children, P_ES measurement is rarely performed in routine paediatric practice. While the lack of robust clincal data partially explains this observation, important limitations of the existing methods to estimate P_PL in children, such as their invasiveness and technical limitations, associated with the lack of reference values for lung and chest wall elastances may also play a role. P_PL and P_L monitoring have numerous potential clinical applications in the PICU to tailor protective MV, but its usefulness is counterbalanced by technical limitations. Paediatric evidence seems currently too weak to consider oesophageal manometry as a routine respiratory monitoring. The development and validation of a noninvasive estimation of P_L and multimodal respiratory monitoring may be worth to be evaluated in the future.

Clinical Challenges in Pediatric Ventilation Liberation: A Meta-Narrative Review

OBJECTIVES

To map the evidence for ventilation liberation practices in pediatric respiratory failure using the Realist And MEta-narrative Evidence Syntheses: Evolving Standards publication standards.

DATA SOURCES

CINAHL, MEDLINE, COCHRANE, and EMBASE. Trial registers included the following: ClinicalTrials.gov, European Union clinical trials register, International Standardized Randomized Controlled Trial Number register.

STUDY SELECTION

Abstracts were screened followed by review of full text. Articles published in English language incorporating a heterogeneous population of both infants and older children were assessed.

DATA EXTRACTION

None.

DATA SYNTHESIS

Weaning can be considered as the process by which positive pressure is decreased and the patient becomes increasingly responsible for generating the energy necessary for effective gas exchange. With the growing use of noninvasive respiratory support, extubation can lie in the middle of the weaning process if some additional positive pressure is used after extubation, while for some extubation may constitute the end of weaning. Testing for extubation readiness is a key component of the weaning process as it allows the critical care practitioner to assess the capability and endurance of the patient's respiratory system to resume unassisted ventilation. Spontaneous breathing trials (SBTs) are often seen as extubation readiness testing (ERT), but the SBT is used to determine if the patient can maintain adequate spontaneous ventilation with minimal ventilatory support, whereas ERT implies the patient is ready for extubation.

CONCLUSIONS

Current literature suggests using a structured approach that includes a daily assessment of patient's readiness to extubate may reduce total ventilation time. Increasing evidence indicates that such daily assessments needs to include SBTs without added pressure support. Measures of elevated load as well as measures of impaired respiratory muscle capacity are independently associated with extubation failure in children, indicating that these should also be assessed as part of ERT.

Continuous noninvasive blood gas estimation in critically ill pediatric patients with respiratory failure

Patients supported by mechanical ventilation require frequent invasive blood gas samples to monitor and adjust the level of support. We developed a transparent and novel blood gas estimation model to provide continuous monitoring of blood pH and arterial CO₂ in between gaps of blood draws, using only readily available noninvasive data sources in ventilated patients. The model was trained on a derivation dataset (1,883 patients, 12,344 samples) from a tertiary pediatric intensive care center, and tested on a validation dataset (286 patients, 4030 samples) from the same center obtained at a later time. The model uses pairwise non-linear interactions between predictors and provides point-estimates of blood gas pH and arterial CO₂ along with a range of prediction uncertainty. The model predicted within Clinical Laboratory Improvement Amendments of 1988 (CLIA) acceptable blood gas machine equivalent in 74% of pH samples and 80% of PCO₂ samples. Prediction uncertainty from the model improved estimation accuracy by 15% by identifying and abstaining on a minority of high-uncertainty samples. The proposed model estimates blood gas pH and CO₂ accurately in a large percentage of samples. The model's abstention recommendation coupled with ranked display of top predictors for each estimation lends itself to real-time monitoring of gaps between blood draws, and the model may help users determine when a new blood draw is required and delay blood draws when not needed.

Frequency and Risk Factors for Reverse Triggering in Pediatric Acute Respiratory Distress Syndrome during Synchronized Intermittent Mandatory Ventilation

Rationale: Reverse triggering (RT) occurs when respiratory effort begins after a mandatory breath is initiated by the ventilator. RT may exacerbate ventilator-induced lung injury and lead to breath stacking.Objectives: We sought to describe the frequency and risk factors for RT among patients with acute respiratory distress syndrome (ARDS) and identify risk factors for breath stacking.Methods: We performed a secondary analysis of physiologic data from children on synchronized intermittent mandatory pressure-controlled ventilation enrolled in a single-center randomized controlled trial for ARDS. When children had a spontaneous effort on esophageal manometry, waveforms were recorded and independently analyzed by two investigators to identify RT.Results: We included 81,990 breaths from 100 patient-days and 36 patients. Overall, 2.46% of breaths were RTs, occurring in 15/36 patients (41.6%). A higher tidal volume and a minimal difference between neural respiratory rate and set ventilator rate were independently associated with RT (P = 0.001) in multivariable modeling. Breath stacking occurred in 534 (26.5%) of 2,017 RT breaths and in 14 (93.3%) of 15 patients with RT. In multivariable modeling, breath stacking was more likely to occur when total airway Δpressure (peak inspiratory pressure - positive end-expiratory pressure [PEEP]) at the time patient effort began, peak inspiratory pressure, PEEP, and Δpressure were lower and when patient effort started well after the ventilator-initiated breath (higher phase angle) (all P < 0.05). Together, these parameters were highly predictive of breath stacking (area under the curve, 0.979).Conclusions: Patients with higher tidal volume who have a set ventilator rate close to their spontaneous respiratory rate are more likely to have RT, which results in breath stacking >25% of the time.Clinical trial registered with ClinicalTrials.gov (NCT03266016).

Extubation Readiness Practices and Barriers to Extubation in Pediatric Subjects

BACKGROUND

Invasive mechanical ventilation is a lifesaving intervention that is associated with short- and long-term morbidities. Extubation readiness protocols aim to decrease extubation failure rates and simultaneously shorten the duration of invasive ventilation. This study sought to analyze extubation readiness practices at one institution and identify barriers to extubation in pediatric patients who have passed an extubation readiness test (ERT).

METHODS

We performed a retrospective chart review of all pediatric subjects admitted between April 2017 and March 2018, and who were on mechanical ventilation. Exclusion criteria were cardiac ICU admission, tracheostomy, chronic ventilator support, limited resuscitation status, and death before extubation attempt. Data with regard to the method of ERT and reasons for delaying extubation were collected.

RESULTS

There were 427 subjects included in the analysis with 69% having had an ERT before extubation. Of those, 39% were extubated per our daily spontaneous breathing trial (SBT) protocol, and the daily SBT failed in 30% but they had passed a subsequent pressure support and CPAP trial on the same day. The most common reasons for failing the daily SBT were a lack of spontaneous breathing (30% [75/252]), being intubated < 24 h (24% [60/252]), breathing frequency outside the target range (22% [55/252]), and not meeting tidal volume goal (14% [34/252]). The most common documented reasons for delaying extubation despite passing daily SBT were planned procedure (29% [26/90]), neurologic status (23% [21/90]), and no leak around the endotracheal tube (18% [16/90]). The median time between passing ERT and extubation was 7 h (interquartile range, 5-10).

CONCLUSIONS

In our institution, there was variation in extubation readiness practices that could lead to a significant delay in liberation from invasive ventilation. Adjustment of our daily SBT to tolerate a higher work of breathing, such as higher breathing frequencies and lower tidal volumes, and incorporating sedation scoring into the protocol could be made without significantly affecting extubation failure rates.

Direction and Magnitude of Change in Plateau From Peak Pressure During Inspiratory Holds Can Identify the Degree of Spontaneous Effort and Elastic Workload in Ventilated Patients

OBJECTIVES

Inspiratory holds with measures of airway pressure to estimate driving pressure (elastic work) are often limited to patients without respiratory effort. We sought to evaluate if measures of airway pressure during inspiratory holds could be used for patients with spontaneous respiratory effort during mechanical ventilation to estimate the degree of spontaneous effort and elastic work.

DESIGN

We compared the direction and degree of change in airway pressure during inspiratory holds versus esophageal pressure through secondary analysis of physiologic data.

SETTING

ICUs at Children's Hospital Los Angeles.

PATIENTS

Children with pediatric acute respiratory distress syndrome with evidence of spontaneous respiration while on pressure control or pressure support ventilation.

INTERVENTIONS

Inspiratory hold maneuvers.

MEASUREMENTS AND MAIN RESULTS

From airway pressure, we defined "plateau - peak pressure" as Pmusc, index, which was divided into three categories for analysis (< -1 ["negative"], between -1 and 1 ["neutral"], and > 1 cm H2O ["positive"]). A total of 30 children (age 36.8 mo [16.1-70.3 mo]) from 65 study days, comprising 118 inspiratory holds were included. Pmusc, index was "negative" in 29 cases, was "neutral" in 17 cases, and was "positive" in 72 cases. As Pmusc, index went from negative to neutral to positive, there was larger negative deflection in esophageal pressure -5.0 (-8.2 to 1.9), -5.9 (-7.6 to 4.3), and -10.7 (-18.1 to 7.9) cm H2O (p < 0.0001), respectively. There was a correlation between max negative esophageal pressure and Pmusc, index (r = -0.52), and when Pmusc, index was greater than or equal to 7 cm H2O, the max negative esophageal pressure was greater than 10 cm H2O. There was a stronger correlation between Pmusc, index and markers of elastic work from esophageal pressure (r = 0.84).

CONCLUSIONS

The magnitude of plateau minus peak pressure during an inspiratory hold is correlated with the degree of inspiratory effort, particularly for those with high elastic work. It may be useful to identify patients with excessively high effort or high driving pressure.

Ventilator Liberation in the Pediatric ICU

Despite the accepted importance of minimizing time on mechanical ventilation, only limited guidance on weaning and extubation is available from the pediatric literature. A significant proportion of patients being evaluated for weaning are actually ready for extubation, suggesting that weaning is often not considered early enough in the course of ventilation. Indications for extubation are often not clear, although a trial of spontaneous breathing on CPAP without pressure support seems an appropriate prerequisite in many cases. Several indexes have been developed to predict weaning and extubation success, but the available literature suggests they offer little or no improvement over clinical judgment. New techniques for assessing readiness for weaning and predicting extubation success are being developed but are far from general acceptance in pediatric practice. While there have been some excellent physiologic, observational, and even randomized controlled trials on aspects of pediatric ventilator liberation, robust research data are lacking. Given the lack of data in many areas, a determined approach that combines systematic review with consensus opinion of international experts could generate high-quality recommendations and terminology definitions to guide clinical practice and highlight important areas for future research in weaning, extubation readiness, and liberation from mechanical ventilation following pediatric respiratory failure.

Lung- and Diaphragm-Protective Ventilation

Mechanical ventilation can cause acute diaphragm atrophy and injury, and this is associated with poor clinical outcomes. Although the importance and impact of lung-protective ventilation is widely appreciated and well established, the concept of diaphragm-protective ventilation has recently emerged as a potential complementary therapeutic strategy. This Perspective, developed from discussions at a meeting of international experts convened by PLUG (the Pleural Pressure Working Group) of the European Society of Intensive Care Medicine, outlines a conceptual framework for an integrated lung- and diaphragm-protective approach to mechanical ventilation on the basis of growing evidence about mechanisms of injury. We propose targets for diaphragm protection based on respiratory effort and patient-ventilator synchrony. The potential for conflict between diaphragm protection and lung protection under certain conditions is discussed; we emphasize that when conflicts arise, lung protection must be prioritized over diaphragm protection. Monitoring respiratory effort is essential to concomitantly protect both the diaphragm and the lung during mechanical ventilation. To implement lung- and diaphragm-protective ventilation, new approaches to monitoring, to setting the ventilator, and to titrating sedation will be required. Adjunctive interventions, including extracorporeal life support techniques, phrenic nerve stimulation, and clinical decision-support systems, may also play an important role in selected patients in the future. Evaluating the clinical impact of this new paradigm will be challenging, owing to the complexity of the intervention. The concept of lung- and diaphragm-protective ventilation presents a new opportunity to potentially improve clinical outcomes for critically ill patients.

Can Computer Decision Support Help Us Follow Our Own Rules in Pediatric Acute Respiratory Distress Syndrome?

Computerized decision support in pediatric #ARDS may improve guideline compliance. Can #MachineLearning improve on this further? @drjonpelly and @cmhorvat discuss a new phase one clinical trial in this month’s @PedCritCareMed.

Real-Time Effort Driven Ventilator Management: A Pilot Study

OBJECTIVES

Mechanical ventilation of patients with acute respiratory distress syndrome should balance lung and diaphragm protective principles, which may be difficult to achieve in routine clinical practice. Through a Phase I clinical trial, we sought to determine whether a computerized decision support-based protocol (real-time effort-driven ventilator management) is feasible to implement, results in improved acceptance for lung and diaphragm protective ventilation, and improves clinical outcomes over historical controls.

DESIGN

Interventional nonblinded pilot study.

SETTING

PICU.

PATIENTS

Mechanically ventilated children with acute respiratory distress syndrome.

INTERVENTIONS

A computerized decision support tool was tested which prioritized lung-protective management of peak inspiratory pressure-positive end-expiratory pressure, positive end-expiratory pressure/FIO2, and ventilatory rate. Esophageal manometry was used to maintain patient effort in a physiologic range. Protocol acceptance was reported, and enrolled patients were matched 4:1 with respect to age, initial oxygenation index, and percentage of immune compromise to historical control patients for outcome analysis.

MEASUREMENTS AND MAIN RESULTS

Thirty-two patients were included. Acceptance of protocol recommendations was over 75%. One-hundred twenty-eight matched historical controls were used for analysis. Compared with historical controls, patients treated with real-time effort-driven ventilator management received lower peak inspiratory pressure-positive end-expiratory pressure and tidal volume, and higher positive end-expiratory pressure when FIO2 was greater than 0.60. Real-time effort-driven ventilator management was associated with 6 more ventilator-free days, shorter duration until the first spontaneous breathing trial and 3 fewer days on mechanical ventilation among survivors (all p ≤ 0.05) in comparison with historical controls, while maintaining no difference in the rate of reintubation.

CONCLUSIONS

A computerized decision support-based protocol prioritizing lung-protective ventilation balanced with reduction of controlled ventilation to maintain physiologic levels of patient effort can be implemented and may be associated with shorter duration of ventilation.

Can visual inspection of the electrical activity of the diaphragm improve the detection of patient-ventilator asynchronies by pediatric critical care physicians?

BACKGROUND

Patient-ventilator asynchronies are challenging during pediatric mechanical ventilation. We hypothesized that monitoring the electrical activity of the diaphragm (EAdi) together with the "standard" airway opening pressure (Pao) and flow-time waveforms during pressure support ventilation would improve the ability of a cohort of critical care physicians to detect asynchronies in ventilated children.

METHODS

We recorded the flow, Pao and EAdi waveforms in ten consecutive patients. The recordings were split in periods of 15 s, each reproducing a ventilator screenshot. From this pool, a team of four experts selected the most representative screenshots including at least one of the three most common asynchronies (missed efforts, auto-triggering and double triggering) and split them into two versions, respectively showing or not the EAdi waveforms. The screenshots were shown in random order in a questionnaire to sixty experienced pediatric intensivists that were asked to identify any episode of patient-ventilator asynchrony.

RESULTS

Among the ten patients included in the study, only eight had EAdi tracings without artifacts and were analyzed. When the Eadi waveform was shown, the auto-triggering detection improved from 13% to 67% (P<0.0001) and the missed efforts detection improved from 43% to 95% (P<0.0001). The detection of double triggering, instead, did not improve (85% with the EAdi vs. 78% without the EAdi waveform; P=0.52).

CONCLUSIONS

This single center study suggests that the EAdi waveform may improve the ability of pediatric intensivists to detect missed efforts and auto-triggering asynchronies. Further studies are required to determine the clinical implications of these findings.